The invention relates to an apparatus for continuously coating band-type substrates in a vacuum coating chamber comprising a plurality of evaporator vessels. The latter form a row of evaporators disposed parallel to each other, spaced approximately equally apart and following the direction of movement of the band. All of the evaporator vessels are made of an electrically conductive ceramic material and are heated by directly passing through a current. Further comprised is a device for the continuous supply of wire to be evaporated to the evaporator vessels.
Prior art apparatus for the continuous coating of band-type substrates in a vacuum coating chamber where the evaporator vessels are disposed along the direction of movement of the band and spaced parallel to one another at equal distances.
Further, an apparatus is known (DE 970 246) which, in order to obtain a greatest possible uniform layer thickness on the substrate to be coated, has chambers which correspond to the evaporator vessels and are disposed in two or more parallel rows. These rows are offset with respect to each other in such a manner that, if looked at from the side, the chambers mutually overlap and thus do not allow an evaporation gap to form.
U.S. Pat. No. 3,563,202 discloses a large number of evaporating cells arranged transversely to the direction of band movement. The heating of the cells is individually controlled, and the cells are continuously moved and resupplied with source material. However, the cells are not suited for the evaporation of metals delivered in wire form.
JP-A-1-219 157 discloses electrically heated evaporating cells spaced apart at equal distances and parallel to the direction of band movement, but without any offset between centerlines of the cells.
These known devices have the disadvantage that the overlap of the evaporation beams of the individual sources causes an irregular coating distribution on the band. In an ideal case, this is a wave-like distribution with maximum and minimum values above and between the vessels. The best-possible layer uniformity is determined by the amplitude of maximum and minimum values. The amplitude itself depends upon the geometric arrangement and the characteristics of the emission (rate distribution) of the individual sources and upon the interaction between the individual sources.
It is possible that the above apparatus according to DE 970 246 improves the layer distribution. The disadvantage, however, is that it is no alternative for high rate coating with a conventional coating rate of greater than 1 .mu.m/sec at a coating width of the band of 3 m, at a maximum, since
1. a continuous supply of wire is not possible and PA1 2. technically, the supply of energy necessary for evaporating the wire is very difficult.